Use of VLC for indoors navigation with RGB LEDs and a-SiC: H photodetector

In this research we present a Visible Light Communication (VLC) system for indoor positioning and navigation. The viability of this methodology was demonstrated in previous work for indoor positioning within the unit navigation cell. In this paper it is proposed to extend this concept for navigation in wider spaces that demand more than one navigation unit. The proposed system uses white RGB LEDs of wide divergence angle and a specific photodetector dedicated to the selective wavelengths detection of red, green and blue light. The photodetector is a multilayered pin-pin heterostructure based on a-SiC:H/a-Si:H, such that the spectral sensitivity can be controlled externally by steady state background light. The RGB emitters of the white LED were modulated with specific bit sequences and frequency to assign different optical excitations to each spatial region. The measurement of the induced photocurrent signal by the detector allows the identification of the position. For this purpose the decoding algorithm for the photocurrent signal processing uses the filtering properties of the photodetector for the recognition of the navigation cell word code, and detection of the wavelength and Fourier analysis for recognition of the signal frequency.